Patent Document 1 discloses a power supply apparatus capable of easily supplying, in a short time, electric power to a reefer container (hereinafter, referred to as “container”) including a refrigeration unit. The power supply apparatus wirelessly supplies electric power to each of the containers as a power-receiving unit using a power-supplying unit provided at each of the containers which are stacked vertically and horizontally. The power-supplying unit includes a primary coil used to supply electric power and a moving mechanism used to move the primary coil, and the power supply apparatus arranges the primary coil to face a secondary coil (a power-receiving coil) provided in the container using the moving mechanism, thereby performing wireless power supply to the container.